Photographic method of obtaining a film transparency



June 19, 1956 G. MORRISON 2,751,294

PHOTOGRAPHIC METHOD OF OBTAINING A FILM TRANSPARENCY Filed Jan. 3, 19552 Sheets-Sheet l INVEN TOR.

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United States Patent PHOTOGRAPHIC METHOD OF OBTAINING A FILMTRANSPARENCY George L. Morrison, Evanston, Ill.

Application January 3, 1955, Serial No. 479,432

12 Claims. (Cl. 95-5) The present invention relates generally to thegraphic arts and more particularly to a method of obtaining a filmtransparency having a plurality of images arranged into a montage formedtherein from printing elements which have relief printing surfaces andinitial film transparencies having images formed therein, the derivedtransparency being subsequently usable in forming a plate for a printingpress.

In the everyday production of certain types of lithographic printingsurfaces, for example, in the practice of the albumen and deep-etchoffset processes, the text and other material to be reproduced aretransferred to a plate which may be used in a printing press by aprocess which requires the use of a photographically reproduced print ortransparency of the material to be reproduced. The photographictransparency used is either a positive or a negative, depending upon theprocess employed in making the plate for the printing press. An involvedand time consuming procedure has generally been required to obtain atransparency which includes both half-tone and line work. It has beenthe practice to make separate transparencies of the half-tone work andof the line work and then assemble these transparencies together bystripping. The term stripping in the graphic arts is used to denote theproper assembly upon a layout of all of the transparencies or film unitsinto the final printing form. After the stripping operation, certainareas, such as for example, the areas between the margins of the varioustransparencies, are darkened in an operation usually referred to asmasking and/ or opaquing. Finally, the stripped, masked, and opaquedfilm assembly is used as is, or is photoprinted to form a suitablecomposite transparency which is used in the subsequent process offorming the final press plate.

The usual manner of forming the initial transparency of the line workhas been to set up the text and other line work to be reproduced in anordinary printing form. This form is then inked and an impression onpaper is made therefrom. Finally, the inked imprint or impression isphotographed to produce the transparency.

There are serious disadvantages to the above procedure of forming theline work transparency. Regardless of how well type, type-slugs, andprinting plates are made, there is a substantial loss in the clarity ofthe outlines in the printing surfaces thereof during the inking andduring the actual printing operation, and this loss is carried over inany photographic operation which involves photographing an inkedimpression from such type or other printing surfaces. Also, the processrequires careful make-ready of the printing form, inking of the form,and the making of an impression on paper, all of which steps involveconsiderable time and require relatively skilled workmanship.

It is apparent that many of the difficulties inherent in the abovedescribed procedure of forming a transparency of the line work, and mostof the disadvantages of that procedure could be avoided by the directphotographing of the printing form, and in the past, many attempts have2,751,294 Patented June 19, 1956 been made to do this. However, due atleast in part to the fact that a printing form is commonly made up ofelements having very uneven reflecting powers, varying from the highreflectance of new, cast type or type-slugs, to the low reflectancecharacteristics of, for example, an oxidized copper plate, very poorresults have generally been obtained in direct photography procedures.In fact, the results have generally been so unsatisfactory that for manyyears it was thought that the direct photography of printing forms wasimpractical and even impossible.

One successful procedure which makes it possible to directly photographthe relief printing surfaces contained in the usual printing form, whichmay include type of various kinds and varieties and printing plates madeof various metals is disclosed in my prior application Serial No.303,391, now Patent No. 2,704,410, of which the present application is acontinuation-in-part. However, it was still considered necessary to formseparate transparencies of some of the half-tone images and then combinethese with the transparency formed from photographing the printing formin a stripping operation. Although various attempts have been made tophotograph paper copy and/ or proofs of half-tone work, none have provensuccessful. In each case, there was a considerable loss of tonal valuesand increased contrast in the transparency for reasons which willhereinafter be made clear. This loss of tonal values and increasedcontrast was so serious that the photographing of paper copy and/orproofs of half-tone work was considered impractical.

It is generally the object of the present invention to provide aprocedure for simultaneous or double photographing of any combination ofrelief printing surfaces with photographic half-tone reproductions and/or photographic reproductions of line work so as to form a compositetransparency suitable for use in the making of a press plate.

In accordance with the present invention, a transparency containing animage to be reproduced is com bined with a light reflective surface in amanner such that it may be photographed without the loss of tonalqualities or increase in contrast, together with relief printingsurfaces, such as may be contained in the usual printing form, which aretreated in the manner set forth in my said prior application, Serial No.303,391, now Patent No. 2,704,410.

The present invention makes possible the obtaining of a much bettercomposite transparency of both line and half-tone work than has beenpossible by any of the heretofore known procedures. The desiredcomposite transparency can be made in a minimum amount of time and witha minimum amount of effort and equipment. Moreover, the practice of theinvention does not impair the type or plates contained in the printingform and does not interfere with the prior or subsequent use of the formor its components.

Oother objects and features of the invention will be come apparent fromthe following description and accompanying drawings in which:

Figure l is a perspective view of a printing form containing variouskinds of relief printing surfaces, together with a specially preparedphotographic reproduction;

Figure 2 is a greatly magnified cross-sectional view of a half-toneimage printed on a paper base indicating the manner in which theincident light rays which strike the paper base are reflected;

Figure 3 is a greatly magnified cross-sectional view of a filmcontaining a half-tone image which has been coated with a reflectivesurface in accordance with the present invention;

Figure 4 is a greatly magnified cross-sectional view showing the coatedfilm of Figure 3 with the addition of a base-board backing member whichfacilitates the bandling of the coated film; and

Figure is a greatly magnified cross-sectional view of a modified form ofreflective reproduction formed in accordance with the present invention,said reflective reproduction being formed by mounting a strip filmcontaining a half-tone image on a metal base.

The printing form illustrated in Figure l is of conventional type, andas such, it includes the usual heavy metal chase 11 for containing thevarious components of the form, furniture (i. e., spacers) 13 and theusual locking wedges or quoins 15 for holding the printing elements inplace in the chase. The printing form may include newly cast type and/or type-slugs, slightly used type, old type that is dirty and oxidized,photo-engravings, stereotypes,

:and other printing plates having surfaces which may be of copper, zinc,brass, steel, nickel, chrome, silver, etc. together with photographicimages which are prepared in accordance with the present invention andmounted above a backing member formed of any suitable material such asmetal, wood, etc. The type and/ or type-slugs and the stereotypes areall generally made of type metal. In the form illustrated in Figure 1, acopper printing plate is illustrated at 17, a zinc photo-engraving inwhich the background forms the relief printing surface at 19, anelectrotype section at 21, a stereotype section at 2.3, a type seetionwhich may be either single type or type-slugs at 25,

and a specially prepared photographic reproduction at 27 Although themanner in which the various relief printing surfaces contained in theprinting form are prepared for photographing is adequately described inmy prior application, Serial No. 303,391, new Patent No. 2,7 04,410, itshall be repeated hereinafter for the sake of convenience. Initially,the printing form is set up with the backing members or blocks whichsupport the photographic reproductions in position but without thephotographic reproduction thereon. The various components or printingelements in the printing form are then treated in the following manner.First, the oxide coatings which are generally present on the reliefprinting surfaces of the printing elements are removed. The oxides arepreferably rei moved from the surfaces of all the metals other than typemetal in the printing form by chemical treatment. In order to minimizeor prevent the reoxidation or spotting of the surfaces during thisprocess, as little water as possible should be present in the chemicalsolution used in the removal of these oxides.

tions, well known to those skilled in the art, can be used Commonchemical soluto remove the oxides from the relief printing surfaces inthe printing form. Volatile solutions are generally preferred since theyshorten the time required for this operation. Examples of suitablesolutions which may be used 7 to remove the oxides from copper and zincare: a 5 per cent solution of hydrochloric acid in anhydrous alcohol fworks very well on copper and to a lesser extent on zinc;

a per cent solution of sulphuric acid in anhydrous alcohol also workswell on copper but is not as efficient as the hydrochloric acidsolution; and a 10 per cent solution of acetic acid in anhydrous alcoholproduces very satisfactory results on zinc.

The appropriate chemical solution can be applied to a printing surfaceby placing a small amount of the chemical solution on a rubber block byspraying, dabbing, or the like, and then passing this block over theprinting surfaces. If the proper chemical solution is used, thistreatprinting surfaces other than the type metal, the surfaces of all ofthe metals in the printing form are subjected to an abrasion treatment.This step serves the following function: it removes the oxide from thesurfaces of any type metal which might be present in the printing form;it removes any oxide which might be reforming on the surfaces other thantype metal in the printing form; and it converts each of the reliefprinting surfaces in the printing form into a substantially uniformmatte finish which is a diffusively reflecting surface, fine enough topermit a high percentage of incident light to obey the cosine law. Theresultant relief printing surfaces have sufficiently similar lightreflectance characteristics to provide, after the hereinafter processsteps are carried out, a composite surface suitable for photographing.

The abrading can be accomplished in various ways, however, particularlysatisfactory results are obtained when the abrading is accomplished bythe use of a clean, resilient surface such as a block of rubber orrubber-like compound, containing fine abrasive particles therein. Anordinary pencil eraser is an example of such material, although a largerblock such as is commonly used in the jewelry polishing industry will befound more practical in commercial operations. The abrasive materialcontained in the resilient block is preferably very fine, such as flourof emery, diatomaceous earth and the like. As previously stated,abrading removes dirt, oxides and the like and converts the reliefprinting surfaces in the printing form to clean matte surfaces havinguniform light diffusion properties. For best results, the abrasiveproduced matte surfaces should not contain any lines large enough to bevisible by the naked eye. A few light strokes of the abrasive carryingblock across the raised printing surfaces in the printing form areusually sutficient to produce the desired result. As the abrasivecarrying resilient block is used, metallic particles are transferredfrom the printing surfaces to its surface, thereby causing its surfaceto become contaminated or loaded? After a short time, the surface of theresilient block would, if not cleared, become sufliciently contaminatedto act as a polishing surface rather than as an abrading surface. It istherefore necessary to frequently clean the surface of the resilientblock so as to assure that it acts as an abrading surface. Both thecleaning and abrading operations can be accomplished in a very shortinterval of time.

After the abrading operation is completed,'thc entire printing form iscoated with a light absorbing or non actinic coating, preferably .byspraying, although this coating can be applied in any other manner.Various materials can be used for the light absorbing coating; the bestcoatings, however, are those which include a suitable light absorbingpigment dispersed in a suitable liquid vehicle. The sprayed coatingshould dry rapidly and should be readily removable from the printingsurfaces, as is required in the next step of the preparation process.The sprayed coating should also be readily removable so that theprinting form and the printing elements therein can be cleaned at theconclusion of the photographing operation. At the same time, the coatingshould not dust or crack and should not be toxic or difficult to use.

A particularly satisfactory coating is produced by a mixture of twoparts of trichlorethylene and one part lamp black, all parts being byvolume. This mixture is cheap and easy to handle. The resultant coatingdries immediately, is easily removed from the type and printing platesurfaces, and does not dust or crack.

Other typesof coatings may, of course, be used. The

' essential thingis the provision of a coating which will not themetallic. oxides reflect actinic light. For example, it is possible toemploy an alcohol base coating, a suitable formula includes one partshellac, six parts dry drop-black, and eight parts methanol, all partsbeing by volume. This coating dries very fast, but in order to make thecoating easily removable from the printing surfaces which are to bephotographed, it is necessary to ink the printing form before thecoating is applied. It is also possible to use coatings which comprisedispersions of pigments other than dropblack, for example, red lead canbe used quite successfully. Also, it is possible to spray the printingform with an optical black lacquer, but materials of this type are notrecommended because of the difficulties experienced in cleaning the typeand other printing elements in the printing form.

As a final step in the preparation of the printing surfaces, thenon-refiecting coating which has been applied to the entire surface ofthe printing form is removed from the relief printing surfaces of theprinting form. The nonreflecting coating which remains thus masks orcovers the entire background of the printing form while the metallicprinting surfaces are completely exposed.

The removal of the non-reflecting coating from the printing surfaces isconveniently accomplished by the use of a flat rubber pad, acloth-covered, rather firm, rubber block, or equivalent means. If thecoating has been applied by the use of the trichlorethylene lamp blackmixture described above, the pad may be used dry and a few light strokesthereof will effect adequate cleaning of the printing surfaces. On theother hand, if an alcohol type coating is used, the printing form shouldbe inked preliminary to the application of the coating and the coatingmay be removed by using a soft pad which has been moistened in naptha,benzene, or other ink solvent.

Various changes may be made in the order of the various steps ofpreparing the printing surfaces in the printing form. For example, theabrading step or the chemical treatment step and the abrading step canbe carried out after the non-actinic coating has been applied to theentire surface of the printing form and then removed from the printingsurfaces. However, when the steps are reversed in this manner, there issome danger that the nonactinic coating will be rubbed elf of thebackground of the printing form.

After the printing elements in the printing form are treated in theabove manner, photographic reproductions which are especially preparedin the manner set forth below may be positioned within the printing formon the surface of an underlying supporting block which also serves toproperly space and position the printing elements in the printing form.Since the printing elements in the printing form are generally laterallyreversed, the images in the photographic reproductions should likewisebe laterally reversed. The supporting block is of appropriate height soas to position the reflective surface of the photograph reproduction atapproximately the same height as the printing surfaces of the printingform. The manner of preparing a photographic reproduction so that it maybe either simultaneously or double photographed (a double exposure takenon the same film) with the prepared printing surfaces in the printingform is described in detail below.

In order to understand the necessity of preparing a photographic printin the manner to be described, it will be helpful to understand whythere is a considerable loss of tonal values with resulting increasedcontrast when a proof of a letter press half-tone image is photographed.The main cause of this loss of tonal values arises from the reflectioncharacteristics of the proof or paper base print. This phenomena isillustrated in Figure 2 wherein a print of a half-tone image 31 is shownon a paper base 33 which is both li ht reflective and light permeable.When the image 31 on the paper base is illuminated with a diffusedsource of light, the light rays strike the surface of the print atvarious angles. The light rays which strike the print at an angle normalto the surface of the print are generally either absorbed or reflected,depending upon whether the rays strike the black dots 35'which form theimage 31 or the area 37 between the dots 35. Where the light rays strikethe surface of the print at an angle other than normal to the surface,the reflection characteristics are not ideal. In Figure 2, there isillustrated a pair of light rays A1 and A: striking the surface of theprint at the same angle. The ray A1 strikes the surface of the print ata point spaced from the dots 35 and is partially reflected along a lineB1. Some of the incident light, however, penetrates the paper base 33where it is diffused and reflected along lines such as for example lineC1. The ray of light A2 on the other hand, strikes the print nearseveral of the half-tone dots 35. A portion of the light of the ray A2is reflected from the surface of the print along a line B2 and a portionof the light is internally reflected along lines such as for example C2within the paper base and absorbed by one or more of the black dots 35.Thus, where the dots 35 are close together as at D, there is less lightbeing reflected back to the viewer than occurs in those areas as at Ewhere the dots 35 are further apart. The result is a loss in tonalvalues or increase in contrast in the shadow and middle tonal values ofthe photographic image. The same is true, of course, when a transparentphotographic image is mounted on a paper base and photographed.

The present invention overcomes the above difiiculties and provides anaccurate means for photographing halftone, line, or other forms ofphotographic images. This is accomplished by first producing an image ofthe desired form on a transparent base and then applying a lightreflective, light impervious surface to the transparent base whichcontains the image with the light reflective surface in intimate contactwith the image. This provides an image which can be photographed withoutloss of tonal values.

Many methods are available for applying a light reflective surface to atransparent base for the purpose of this invention. One of the easiestmethods involves spraying or brushing a liquid composition containinglight reflective particles such as aluminum particles or similar brightmetallic particles on the base and in contact with the image therein.Ordinary aluminum paint or lacquer, for example, has been found to besatisfactory for this purpose. It has been found necessary to apply theliquid composition in a very thin layer so as to prevent stratificationbetween the metallic particles and the liquid vehicle.

When the transparent base containing the image consists of strip film,the light reflective surface may be pro vided by securing the strip filmto a highly polished surface as, for example, a highly polished sheet ofaluminum or tin foil, metal acetate sheeting, or other metallizedsurface.

For the purpose of the present invention, it is essential that the lightreflective surface be in intimate contact with the image. Where theimage is produced on an extremely thin film such as ordinary strip film,either side of the film may be secured to the light reflective surface.However, when the transparent base has an appreciable thickness, of theorder of a few mils, it becomes important to apply light reflectivesurface to the surface which contains the image. In the case of anordinary photographic film, this means that the light reflective surfacemust be applied to the emulsion surface of the film and that the imagebe subsequently photographed through the transparent base which overliesthe image.

Three examples of transparent photographic images which are providedwith light reflective surfaces in accordance with the present inventionare illustrated in Figures 3, 4, and 5. In Figure 3, the referencenumeral 39 indicates a film base having an emulsion surface 41 whichincludes a half-tone image 43.- A light reflective metal coating 45covers the entire emulsion'surface 41. This light reflective coating maybe formed of a material such as aluminum powder and be applied to theemulsion surface 41 by spraying, brushing, roller coating, etc.

It is generally preferable to mount a coated transparency such as isillustrated in Figure 3 on a supporting member 47 formed of press board,cardboard, metal, or the like as shown in Figure 4 so as to maintain thecoated transparency in as flat a condition aspossible.

of extremely small thickness which includes a half-tone image 51 isadhesively secured to a metal supporting a member 53 which may consistof any light reflective metal such as a bright, metallic coated plate, ametal sheet, or a metal foil.

The coated films described above may be photographed in the usual mannerwithout any noticeable loss of tonal values since practically all of thelight rays such as the rays F and H, which strike the reflective surfacebetween the dots of the half-tone images are reflected back along linessuch as the lines G and I with the same intensity.

When the coated, transparent reproduction is combined with otherprinting elements for simultaneous photographing, it is, of course,necessary to have the reflection characteristics of the transparentreproduction match that of the other printing elements. It has beenfound that the re- .fiectance characteristics of both the transparentreproduction and the printing elements are approximately the same -whenthey are prepared in the manner described above.

However, even better matching of the reflection characteristics isobtained when the upwardly facing surface of the transparentreproduction (i. e., when the surface of the reproduction opposite thatto which the light reflective -material is applied) is abraded. Theabrading can be accomplished in various ways and particularlysatisfactory results are obtained when the surface is abraded by the useof a cotton pad containing pumice particles or by the use of a block ofrubber or rubber-like compound containing very finely divided abrasivematerial. The abrading transforms the upper surface of the film ortransparency into a matte finish, that is, a uniform, ditfusivelyreflecting surface.

If the coated transparent reproduction is to be inserted in the printingform, the image therein should be laterally .reversed and thetransparent reproduction should be of suitable dimensions for insertionin the desired location within the printing form. A convenient method ofpositioning the coated transparency within the printing form his toplace suitably-sized strips of double faced Scotch j tape, that is,Scotch tape which has an adhesive surface on both of its sides, on theback side of the reflective surface or the supporting member which issecured to the reflective surface, drop a few drops of trichloroethyleneonto the black coated base, and then place the coated transparentreproduction in the selected location within the printing form and pressdownwardly. There will be sufiicient adherence between the Scotch tapeand the underlying block due to the trichloroethylene softening 1 boththe black coating and the Scotch tape adhesive to prevent thedislocation of the mounted transparent reproduction during thesubsequent photographing operation. The mounting block should be ofsuitable height so that the reflective surface to which the transparentreproduction is bonded lies at approximately the same height as-therelief printing surfaces within the printing form.

After the transparency is mounted within the printing form, the form isready for photographing. This may be effected by the use of an ordinaryphoto-engravers camera or similar equipment. One particularly effectivearrangement has been described in my prior patent, No. 2,609,623.

In certain cases, such as where illustrations fit close to type, wheretype is set irregularly around an illustration,

where it is desired to have type overprint illustrations,

' etc., the above described procedure cannot be followed.

in these special cases, it is necessary to prepare the printing form andthe transparencies in the manner described. above but instead of placingthe prepared transparency in the printing form for subsequentsimultaneous photographing, the printing form and preparedtransparencies are maintained as separate entities and photographed.iseparately. on the same film by double exposing the film;

The printing form and the reflective images must be properly positionedduring the. photographing so that they register properly on the doubleexposed film. If desired,

printed with the printing form, must also be laterally reversed so theywill read the same as the printing form (which is wrong-reading). Theselaterally reversed images can generally be made from conventional copyand standard cameras by means of a prism, a straightline image reverser,or by photographing on strip film and then flopping the film. There areother means of obtaining laterally reversed images, such as making acontact print on Autopositive film.

in the foregoing, there has been described an improved method ofpreparing printing elements and photographic reproductions for eithersimultaneous or double photographing. The practice of the inventionprovides a convenient and economical means for producing transparenciesof both line and half-tone images for subsequent use in preparing pressplates.

It will be appreciated that various modifications can be made to theabove described method without departing from the scope of the presentinvention.

The present invention is a continuation-in-part of my prior application,Serial No. 303,391, filed August 8, 1952, now Patent No. 2,704,410,which in turn was a continuation-in-part of an earlier application,Serial No. 20,214, filed April 10, 1948, now Patent No. 2,624,700.

1 claim:

1. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therein, comprising the steps of, assembling selectedprinting elements into a printing form with all of the relief printingsurfaces of said printing elements at approximately the same height,abrading the relief printing surfaces with a clean, resilient surfacecontaining very fine abrasive particles therein to produce on saidrelief printing surfaces a clean, diifusively reflecting finish ofsufficient fineness so that the individual lines in the surfaces are notvisible to the naked eye, applying a light absorbing coating to theentire surface of the printing form, removing said coating from therelief printing surfaces while leaving the coating intact on the othersurfaces of the printing form, applying a light reflective surface ontoat least one of said transparent bases in intimate contact with theimage formed therein, and then photographing said prepared printing formand each rcflectively surfaced, transparent base on the samephotographic film and in suitable registration.

2. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therein, comprising the steps of, assembling selectedprinting elements into a printing form with all of the relief printingsurfaces of said printing elements at approximately the same height,applying a light absorbing coating to the entire surface of the printingform, removing said coating from the relief printing surfaces whileleaving the coating intact on the other surfaces of the printing form,abrading the relief printing surfaces with a clean, resilient surfacecontaining very fine abrasive particles therein to produce on saidrelief printing surfaces a clean, ditfusively reflecting finish ofsufficient fineness so that the individual lines in the surfaces are notvisible to the naked eye, applying a light reflective surface onto atleast one of said transparent bases in intimate contact with the imageformed therein, and then photographing said prepared printing form andeach reflectively surfaced, transparent base on the same photographicfilm and in suitable registration.

3. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therein, comprising the steps of, assembling selectedprinting elements into a printing form with all of the relief printingsurfaces of said printing elements at approximately the same height,abrading the relief printing surfaces with a clean, resilient surfacecontaining very fine abrasive particles therein to produce on saidrelief printing surfaces a clean, diffusively reflecting finish ofsufficient fineness so that the individual lines in the surfaces are notvisible to the naked eye, applying a light absorbing coating to theentire surface of the printing form, and then removing said coating fromthe relief printing surfaces While leaving the coating intact on theother surfaces of the printing form, applying a thin film of lightreflective metal particles onto at least one of said trans parent basesin intimate contact with the image formed therein, and thenphotographing said prepared printing form and each reflectivelysurfaced, transparent base on the same photographic film and in suitableregistration.

4. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therin, comprising the steps of, assembling selectedprinting elements into a printing form with all of the relief printingsurfaces of said printing elements at approximately the same height,abrading the relief printing surfaces with a clean, resilient surfacecontaining very fine abrasive particles therein to produce on saidrelief printing surfaces a clean, diifusively reflecting finish ofsufiicient fineness so that the individual lines in the surfaces are notvisible to the naked eye, applying a light absorbing coating to theentire surface of the printing form and then removing said coating fromthe relief printing surfaces while leaving the coating intact on theother surfaces of the printing form, applying a light reflective surfaceonto selected transparent bases in intimate contact with the imagesformed therein, abrading the surfaces of said selected transparent baseswhich are opposite to said light reflective surfaces, and thenphotographing said prepared printing form and each of said abraded andreflectively surfaced transparent base in the same photographic film andin suitable registration.

5. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therein, comprising the steps of, assembling selectedprinting elements into a printing form with all of the relief printingsurfaces of said printing elements at approximately the same height,abrading the relief printing surfaces with a clean, resilient surfacecontaining very fine abrasive particles therein to produce on saidrelief printing surfaces a clean, diffusively reflecting finish ofsufificient fineness so that the individual lines in the surfaces arenot visible to the naked eye, applying a light absorbing coating to theentire surface of the printing form, removing said coating from therelief printing surfaces while leaving the coating intact on the othersurfaces of the printing form, applying a thin film of light reflectivemetal particles onto selected transparent bases in intimate contact withthe images formed therein, abrading the surfaces of said selectedtransparent bases which are opposite to said light reflective surfacesand then photographing said prepared printing form and each of saidabraded and reflectively surfaced transparent base in the samephotographic film and in suitable registration.

6. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therein, comprising the steps of, assembling selectedprinting elements into a printing form with all of the relief printingsurfaces of said printing elements at approximately the same height,removing the oxides from each of the relief printing surfaces of theprinting form, abrading the relief printing surfaces with a clean,resilient surface containing very fine abrasive particles therein toproduce on said relief printing surfaces a clean, diffusively reflectingfinish of suificient fineness so that the individual lines in thesurfaces are not visible to the naked eye, applying a light absorbingcoating to the entire surface of the printing form, removing saidcoating from the relief printing surfaces while leaving the coatingintact on the other surfaces of the printing form, applying a lightreflective surface onto at least one of said transparent bases inintimate contact with the image formed therein, and then photographingsaid prepared printing form and each reflectively surfaced, transparentbase on the same photographic film and in suitable registration.

7. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therein, which comprises the steps of, assembling variousdesired relief printing surfaces into a printing form with all of therelief printing surfaces at approximately the same height, abrading therelief printing surfaces with a clean, resilient surface containing veryfine abrasive particles therein to produce on said relief printingsurfaces a clean, difiusively reflecting finish of sufficient finenessso that the individual lines in the surfaces are not visible to thenaked eye, applying a light absorbing coating to the entire surface ofthe printing form, re moving said coating from the relief printingsurfaces while leaving the coating intact on the other surfaces of theprinting form, applying a light reflective surface onto desiredtransparent bases in intimate contact with the images formed therein,mounting said reflectively surfaced transparent bases in selectedpositions within said printing form with said light reflective surfaceslowermost and at approximately the height of said relief printingsurfaces, and then photographing said printing form.

8. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therein, which comprises the steps of, assembling variousdesired relief printing surfaces into a printing form with all of therelief printing surfaces at approximately the same height, applying alight absorbing coat ing to the entire surface of the printing form,removing said coating from the relief printing surfaces while leavingthe coating intact on the other surfaces of the printing form, abradingthe relief printing surfaces with a clean, resilient surface containingvery fine abrasive particles therein to produce on said relief printingsurfaces a clean, diffusively reflecting finish of sufficient finenessso that the individual lines in the surfaces are not visible to thenaked eye, applying a light reflective surface onto desired transparentbases in intimate contact with the images formed therein, mounting saidreflectively surfaced transparent bases in selected positions withinsaid printing form with said light reflective surfaces lowermost and atapproximately the height of said relief printing surfaces, and thenphotographing said printing form.

9. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therein, which comprises the steps of, assembling variousdesired relief printing surfaces into a printing form with all of therelief printing surfaces at approxiare not visible to the naked eye,applying a light absorbing coating to the entire surface of the printingform, removing said coating from the relief printing surfaces whileleaving the coating intact on the other surfaces of the printing form,applying a thin film of light reflective metal particles onto desiredtransparent bases in intimate contact with the images formed therein,mounting said refiectively surfaced transparent bases in selectedpositions within said printing form with said light reflective surfaceslowermost and at approximately the height of said relief printingsurfaces, and then photographing said printing form.

10. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therein, which comprises the steps of, assembling variousdesired relief printing surfaces into a printing form with all of therelief printing surfaces at approxirnately the same height, abrading therelief printing surfaces with a clean, resilient surface containing veryfine abrasive particles therein to produce on said relief printingsurfaces a clean, diffusively reflecting finish of sufficient finenessso that the individual lines in the surfaces are not visible to thenaked eye, applying a light absorbing coating to the entire surface ofthe printing form, re-

moving said coating from the relief printing surfaces while leaving thecoating intact on the other surfaces of the printing form, applying alight reflective surface onto desired transparent bases in intimatecontact with the images formed therein, abrading said desiredtransparent Y bases on the surfaces opposite to said light reflectivesurfaces, mounting said abraded and refiectively surfaced transparentbases in selected positions within said printing form with said lightreflective surfaces lowermost and at approximately the height of saidrelief printing surfaces, and then photographing said printing form.

11. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therein, which comprises the steps of, assembling variousdesired relief printing surfaces into a printing form moving saidcoating from the relief printing surfaces while leaving the coatingintact on the other surfaces of the printing form, applying a thin filmof light reflective metal particles onto desired transparent bases inintimate contact with the images formed therein, abrading the surfacesof said desired transparent bases which are opposite to said lightreflective surfaces, mounting said abraded and reflectively surfacedtransparent bases in selected positions within said printing form withsaid light reflective surfaces lowermost and at approximately the heightof said relief printing surfaces, and then photographing said printingform.

12. The method of obtaining a film transparency having a plurality ofimages arranged into a montage formed therein from printing elementswhich have relief printing surfaces and transparent bases which haveimages formed therein, which comprises the steps of, assembling variousdesired relief printing surfaces into a printing form with all of therelief printing surfaces at approximately the same height, removing theoxides from each of the relief printing surfaces of the printing form,abrading the relief printing surfaces with a clean, resilient surfacecontaining very fine abrasive particles therein to produce on saidrelief printing surfaces a clean, difiusively reflecting finish ofsufiicient fineness so that the individual lines in the surfaces are notvisible to the naked eye, applying a light absorbing coating to theentire surface of the printing form, removing said coating from therelief printing surfaces while leaving the coating intact on the othersurfaces of the printing form, applying a light reflective surface ontodesired transparent bases in intimate contact with the images formedtherein, mounting said reflectively surfaced transparent bases inselected positions within said printing form with said light reflectivesurfaces lowermost and at approximately the height of said reliefprinting surfaces, and then photographing said printing form.

References Cited in the file of this patent UNITED STATES PATENTS1,669,821 Grass May 15, 1928

1. THE METHOD OF OBTAINING A FFILM TRANSPARENCY HARVING A PLURALITY OFIMABES ARRANGED INTO A MONTAGE FORMED THEREIN FROM PRINTING ELEMENTSWHICH HAVE RELIEF PRINTING SURFACES AND TRANSPARENT BASES WHICH HAVEIMAGES FORMED THEREIN, COMPRISING THE STEPS OF, ASSEMBLING SELECTEDPRINTING ELEMENTS INTO A PRINTING FORM WITH ALL OF THE RELIEF PRINTINGSURFACE OF SAID PRINTING ELEMENTS AT APPROXIMATELY THE SAME HEIGHT,ABRADING THE RELIEF PRINTING SURFACES WITH A CLEAN, RESILIENT SURFACECONTAINING VERY FINE ABRASIVE PARTICLES THEREIN TO PRODUCE ON SAIDRELIEF PRINTING SURFACES A CLEAN, DIFFUSIVELY REFLECTING FINISH OFSUFFICIENT FINENESS SO THAT THE INDIVIDUAL LINES IN THE SURFACES ARE NOTVISIBLE TO THE NAKED EYE, APPLYING A LIGHT ABSORBING COATING TO THEENTIRE SURFACE OF THE PRINTING FORM, REMOVING SAID COATING FROM THERELIEF PRINTING SURFACES WHILE LEAVING THE COATING INTACT ON THE OTHERSURFACES OF THE PRINTING FORM, APPLYING A LIGHT REFLECTIVE SURFACE ONTOAT LEAST ONE OF SAID TRANSPARENT BASES IN INTIMATE CONTACT WITH THEIMAGE FORMED THEREIN, AND THEN PHOTOGRAPHING SAID PREPARED PRINTING FORMAND EACH REFLECTIVELY SURFACE TRANSPARENT BASE ON THE SAME PHOTOGRAPHICFILM AND IN SUITABLE REGISTRATION.